关键词: 单核增生性李斯特菌, hly基因, 同源重组, 生物特性

Abstract: This study aimed to elucidate the effect of hly gene on the virulence of Listeria monocytogenes. We constructed a hly gene knockout mutant strain EGD-eΔhly from wild-type L. monocytogenes EGD-e by using a shuttle vector through homologous recombination. Biological characterization showed that there was no difference between the growth status of the mutant and parent strains. However, the mutant strain lost hemolytic activity, the cell invasion ability was decreased and there was no toxicity observed in animals receiving intraperitoneal injection at a concentration of 107 cells/mL. At the transcriptional level, the knockout of hly gene down-regulated the expression levels of virulence genes inlC and prfA by 81% and 76% respectively and up-regulated the expression levels of actA and plcB genes by 2.7 and 1.8 times, respectively. This paper may provide a basis for the study of the pathogenic mechanism of Lm.

Key words: Listeria monocytogenes, hly gene, homologous recombination, biological characteristics